Process for polymerizing propylene wherein the titanium halide particle size is at least 150 microns



Feb. 2, 1965 PROCESS FOR POEYMERIZING PROPYLENE WHEREIN THE FIG..Z.

POLYMER PARTICLE SIZE DISTRIBUTION SIEVE SIZE (MESH MICRONS FIG.2.

POLYMEI? PART/0L5 SIZE DISTRIBUTION SIEVE SIZE (MESH MIGRONS n F. HOEG ETAL 3,168,506

TITANIUM HALIDE PARTICLE SIZE IS WEIGHT PERCENT AT LEAST 150 MICRONS Filed July 6, 1961 g} Large Particles of TiCI Comp. Used I50 3} Small Particles of Ticl Comp. um 15,

c A f 0 J 23% 2% 92% 3% 8'6 85 2S 15 E75 Eras 2149 ?IT! 2250 2840 TiCl C0mp.- Et AlCl+ 7.5 PSIAHZ A (8} Large Particle Size of Tim; Comp. Used I50 2} Small Particle Size of Tic]; Comp. Used 75,) A

1 & E z 0 2% 2% 92% 3% 8 88 88 D. F. HOEG A. B. STRYKER INVENTORS ATTORNEY United States Patent 3,168,506 PRQCESS FOR EGLYMEREZING PRQPYLENE WHERElN THE TiTANlUlVi HALIDE PARTI- CLE SEZE l5 AT LEAST 150 MICRONS Bonaltl F. Hoe-g, Roelsville, and Abner Bartlett Eatrylter, .l'r., West Severna Park, Md., assignors to W. R. Grace 5; Co., New York, N311, a corporation 0? Qonnecticut Filed Jul 6, 1961, Ser. No. 1 2,233 o Claims. (till. Zeb-93.7)

This invention relates to a process for polymerizing propylene to high conversions and to the resulting novel form of polypropylene. In one aspect, it relates to the production of large discreteplatelets of free-flowing polypropylene. l'n another particular aspect, it relates to a method for polymerizing propylene without the formation of polymer deposits in the process equipment during polymerization.

It is well known that propylene can be polymerized to relatively high molecular weight solid polymer by subjecting the monomer in liquid form to a catalyst comprised of titanium itrichloride and an activator such as dicthyl aluminum chloride This polymerization process is normally carried out as a batch operation but a continuous operation can be used. Anhydrous and oxygen-free conditions must be maintained throughout the polymerization since the catalyst is deactivated with water or oxygen.

Unfortunately, the polymer product is usually produced in a form such that the apparatus used for polymerization becomes fouled therewith. A portion of the product obtained with the aforementioned catalyst system exhibits a crystalline structure by X-ray analysis. This crystalline portion of the polymer is particularly difiicult to remove from the surfaces of the reactor bec-aues it is substantially insoluble in the usual hydrocarbon solvents, such as the parafiins, including for example, the pentanes, hexanes, octancs, decanes, and the like, and is also insoluble in oxygen-containing organic solvents such as aldehydes and ketones.

The ensuing polymer deposition on the reactor surfaces is largely objectionable because it reduces the ca.- pacity of the reactor and results in ineliicient plant utilization. it also interferes with proper heat transfer, may cause plugging of the reactor or otherwise impair the control of the polymerization reaction, thereby producing interior or non-uniform polymer.

Because this polymeric deposition has a low degree of solubility in readily available solvents, it has heretofore been removed largely by scraping, burning or sand blasting the coated surfaces. These methods of cleaning the eposition from the equipment surfaces are impractical due to the abnormally rapid wear and high replacement cost of equipment so treated.

It is an object of the present invention to provide an improveed polymerization process and product whereby high conversions to substantially free-flowing polymer are obtained with little or no deposit of polymer product on the reactor surfaces.

In summary, this invention is directed to polymerizing liquid propylene under an inert atmosphere at a polymerization temperature in the range of 20 to 90 C., and a pressure in the range 150 to 690 p.s.i.a. in the presence of a catalyst comprised of a TiCl composition and diethyl aluminum chloride, said TiC1 composition having the formula 3TiCl .AlCl and said TiCl composition having a particle size of about 150 microns and larger.

The TiCl composition, 3TiCl .AlCl is a well-known material of commerce, and may be prepared, for example, by the well-known high temperature reduction of TiCL, with aluminum, i.e., 3TiCl +Al- 3TiCl +AlCl When prepared in this way, the material is a homogeneous mixture of Titll and AlCl in the mole ratio of 3:1.

Conversions as high as 98% have been attained by the practice of this invention. As a result, monomer recycle requirements are decreased thus producing a greater product yield for a given size of equipment than methods heretofore employed. Due to the relative cleanness of the reactor surfaces, there is comparatively little interference with heat transfer and increased control of the polymerization reaction is possible.

The polymer produced by the invention is comprised of free-flowing, discrete, fiat platelets about 5 to 10 mm. in size on the average. These polymer particles are crystalline to X-rays and have an apparent density as high as 0.895 g./cc. as measured in a density gradient column at 25 C.

The polymerization temperature may be in the range of about 20 to 0., although temperatures between about 50 and 80 C. are preferred. The preferred pressure is substantially the vapor pressure of liquid propylene at the particular polymerization temperature. Higher ressures up to 5000 p.s.i.a. or pressures to any value can be used if desired. A mole ratio of the diethyl aluminum chloride to the TiCl composition of about 2 to 4:1 is preferred, although ratios as high as l to 8:1 are suitable.

For a better understanding the invention will now be illustrated by actual operating examples.

EXAMPLE 1 Preparation of catalyst The TiCl composition was obtained commercially and had an actual composition of 77.68% TiCl and 22.32% AlCl This composition had been ball-milled by the manufacturer and had particles as large as 250, and larger, and an average particle size of about 15 to 50 The TiCl composition was placed on the top pan of a set of sieves in a dry box under an inert atmosphere of argon and the entire set of sieves was mcchanically shaken for /2 to /4 of an hour. Two steel balls were placed on each pan to aid the operation. Some runs were made using the large size particles i), and other runs were made using the small size particles 75u).

EXAMPLE I-A Polymerization of propylene The reactor was a 1 liter stainless steel pressure reactor equipped with a mechanical stirrer and means for introducing the reaction components. In this run (as roll as in the other runs tabulated) 0.52 grams of the particular size TiCl composition was added to the reactor under a blanket of nitrogen. The reactor contained 1 atmosphere of nitrogen. 200 grams of liquid propylene was then added and the reactor was heated to the reaction temperature of about 64 C. The pressure in the reactor was substantially the pressure or" liquid u propylene at about 64 C., i.e., about 380-460 p.s.i.g. 2.13 ml. of a solution of dicthyl aluminum chloride and hexane containing 3.33 millimoles of diethyl aluminum chloride per milliliter of hexane was blown into the reactor. The amount of diethyl aluminum chloride used was based on a 2:1 mole ratio of diethyl aluminum chloride to the TiCl composition. At the end of one hour the unreacted monomer was vented to the hood and the reactor cooled and opened. The entire reactor product was recovered and allowed to stand exposed to to air. The yield was 113 grams.

In certain runs (see tables below) hydrogen was added before the propylene to reduce the molecular weight of the product. 7 /2 p.s.i.a. hydrogen was used, although as much as 100 p.s.i.-a. or higher can be used if desired. In these runs, the same general result was obtained with the large size particles 150 r) of the TiCl composition, i.e., large, discrete platelets of free-flowing polymer were produced with almost no film forming on the reactor surfaces. When hydrogen was used with the small size particles 75 1) of the TiC1 composition, a fine talcumlike product was still produced, but surprisingly, very little film formed on the reactor surfaces.

After weighing, the polymer was placed on the .top pan of a set of sieves and the entire set was mechanically shaken for /2 to /i of an hour. Two steel balls were placed on each pan to aid the operation. Each fraction was then weighed, and its reduced specific viscosity (RSV) determined by dissolving 0.1 gram of product in 100 cc. Decalin at 135 C.

The isotacticity of each polymer fraction was determined by measuring the insolubility of the polymer in boiling heptane. in each case the insoluble high-molecular-weight isotactic polypropylene was recovered and found to be a certain percent by weight of the unextracted polymer.

' The experimental results are tabulated in Tables I, II and Ill. The formula for determining catalyst activity is grams of polymer/ grams of TiCl composition/hour.

In Table I, where large particle size TiCl composition 150 was used, polymer particles in all size distributions were hard, discrete platelets, free-flowing with no apparent inter-particle fusion. Almost no film was present on the reactor surfaces.

In Table II, where small particle size TiCl composition 75 was used, the resulting polymer was fine talcumlike in appearance. In those runs where hydrogen was not used, a large amount of film formed on the reactor surfaces, but in those runs where hydrogen was used, very little film formed on the reactor surfaces.

In Table III, the results are shown for a run using unfractionated catalyst and a run using medium particle size catalyst 75 150/L) with hydrogen. In the run using unfractionated catalyst, mostly fine particle size polymer was produced with a large amount of film forming on the reactor surfaces. In the run using medium particle size catalyst and hydrogen, a large amount of small particle size polymer was produced with little film forming on the reactor surfaces.

All the runs listed in Tables I and II are graphically illustrated in FIGURES 1 and 2. Each of these runs is numbered to correspond to its graph, for example, run lA is found in FIGURE 1 at A.

In general, over 80% of the polymer particles produced by the large particle size TiCl composition 150 were larger than mesh (250p). The small particle size TiCl composition i) formed mostly fine particle size polymer and less than 30% of the polymer was larger than 60 mesh (ZSQu). Almost all of the polymer formed with the line particle size TiCl composition where hydrogen was not used, and which was classified as the on 20 fraction, consisted of film scraped from the reactor walls, stirring blade and shaft.

The polypropylene product of this invention may be purified and recovered by techniques well-known in the art. For example, the crude polymer may be washed with an alcohol such as methanol. There is no apparent change in the appearance of the polymer after such purification.

The high bulk density particles of this invention have obviously good processability characteristics. They are in a commercially usable form as produced, whereas finely divided polymer particles pack easily and must usually be molded and pelletized before use.

The uses of the polypropylene of this invention are analogous to those prepared by prior art procedures. The solid polymer can be used to make molds, film, filament, piping, tubing, and the like, using substantially the same equipment and techniques customary for the solid polypropylene of the prior art.

TABLE I.-POLYMER PARTICLE SIZE DISTRIBUTION AND PROPERTIES [Obtained with large particle size TiCl composition 150}L Percent Mesh Size On 20 On 60 On On On On 200 Thru 209 Run Conver- Yield, g. Activity Hz sion (p.s.i.a.)

Particle Size @840 (2250;!) 2 177,1) (5149 (5125 (275a) 75 1A 56.5 113 216 0 Weight 77.6 21.4 2.1 1.3 1.0 3.5 4.4

' Percent Heptane Ins 96. 6 96. 5 96.1 95.9 95.6 95. 9 94. 7 12. 3 12.4 12.4 12.9 12.5

' 1B 66 132 252 0 Weight (g.) 39. 4 59. 9 9 5 3. 2 2. 9 9. 8 4. 4

Percent Heptane l sol 96. 3 96.4 96.2 96. 4 96. 4 96.1 95.7 15. 2 15.1 17. 0 17. 2 16.6 16. 7 16. 8

2B 42. 5 85 163 7. 5 Weight (g.) 63.1 18.7 0. 9 0.5 0.4 0.6 0. 6

Percent Heptane Insol 95. 6 95. 4 SV 3. 0 3.1 3 0 2C 98. 5 197 379 7. 5 Weight (g.) 121. 4 49. 8 4.0 2.0 1. 3 3.1 5. 8

Percent Heptane lusol 93. 4 93. 2 89.1 SV 1.9 2. 2 2.1 1- 9 Percent Mesh Size On 20 On 60 On 80 On 100 On 120 On 200 Thru 200 Run Conver- Yield, g. Activity Hg sion (p.s.i.a.)

Particle Size (5840 @250 aim) (2149a) @125 am) 75p) 1O 60. 5 121 235 Weight a 29. 3 24. 3 13. 4 7. 2 6.8 18.0 15.9

Percent Heptane Tnsol 91.1 94. 7 94. 5 94. 6 93. 9 94. 0 93. 6 RSV 14.2 15.0 14.8 1D 51.0 102 195 0 Weight (g) a 13. O 22. 8 15.0 7. 8 7.4 17. 3 13.8

Percent Heptane Insol 94. 0 95. 9 95. 4 95. 6 95.3 95.2 94. 6 RSV .1 15. 4 16. 3 17.3 16.0 15. 3 2D 47. 5 95 180 7. 5 Weight (g.) 3.0 29.0 13. 3 8. 7 5. 4 15. 7 16.0

Percent I-Ieptane Insol 94. 3 93. 6 93. 6 RSV 2. 4 1. Gel 2.4 2. 4 2E 29. 5 59 110 7. 5 Weight (g.) 0.8 23. 8 12. 7 6. 8 4.1 6. 7 1. 9

Percent Heptane Insol 90.5 91.1 89.8 RSV 4. 0

11 Film was segregated in this fraction.

TABLE III.- POLYMEP. PARTICLE SIZE DISTRIBUTION AND PROPERTIES [Obtained with medium particle size and uniractionated TiOl; composition] Percent Mesh Size On On 60 On 80 On 100 On 120 On 200 Thru 200 Run Convcr- Yield, g. Activity H sion (p.s.i.a.)

Particle Size (5840 1) (225011) (2177c) (2149;!) (2125 (275 75 Weight (lgl.) 24.4 98.9 10.3 75 Percent "ptane 2155,. i w 5 173 336 111501": s2. 0 91.8 90. 9 RSV 2. 2 2. 3

Unfecflonlitiil iiiaatat 7 6 6 ated 81.0 162 311 0 111501 5 9&1 RSV 2s. 0 20. 2 20. 3

e Film was segregated in this fraction.

We claim:

1. In the process which comprises polymerizing liquid propylene to a normally solid polymer in a polymerization zone at a temperature in the range 20 to 90 C., and

a pressure in the range 150 to 690 p.s.i.a., in the presence of a catalyst consisting essentially of a TiCl composition and diethyl aluminum chloride, said TiCl composition having the formula 3TiCl .AlCl the improvement in which the said TiCl composition has a particle size of at least about 150 microns with exclusion of particles of ratio of diethyl aluminum chloride to the TiCl composition is 1-8: 1.

3. The process according to claim 2 wherein the mole ratio of diethyl aluminum chloride to the TiCl composition is 2: 1.

4. The process according to claim 3 wherein the polyrnerization temperature is about C. and the pressure is about 380 to 400 psig.

5. The process according to claim 4 wherein about 7 to p.s.i.a. of hydrogen is added to the polymerization zone.

6. A process for substantially eliminating the fouling eiiects and obtaining high conversions in the polymerization of liquid propylene under an inert atmosphere, at a polymerization temperature in the range 20 to 90 C., and a pressure in the range to 690 p.s.i.a., in the presence of a catalyst comprised of a TiCl composition and diethyl aluminum chloride, said TiCl composition having the formula 2TiCl .AlCl the improvement in which the said TiCl composition has a particle size of at least 150 microns with exclusion of particles of a size less than 150 microns.

References Cited in the file of this patent UNITED STATES PATENTS 3,010,952 Lovett et a1. Nov. 28, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,168 ,506 February 2 19o5 Donald F. Hoeg et al.

that error appears in the above numbered pat- It is hereby certified ent requiring correction and that the said Letters Patent should read as corrected below Columns 5 and 6 TABLE In, first column heading, for "Run" read Catalyst Size Signed and sealed this 22nd day of June 1965 (SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Altcsting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,168 ,506 February 2 1965 Donald F. Hoeg et a1.

pears in the above numbered pat- It is hereby certified that error ap d Letters Patent should read as ent req'iiring correction and that the sai corrected below.

Columns 5 and 6 TABLE III, first column heading, for "Run" read Catalyst Size Signed and sealed this 22nd day of June 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aitnsting Officer Commissioner of Patents 

1. IN THE PROCESS WHICH COMPRISES POLYMERIZING LIQUID PROPYLENE TO A NORMALLY SOLID POLYMER IN A POLYMERIZATION ZONE AT A TEMPERATURE IN THE RANGE 20 TO 90*C., AND A PRESSURE IN THE RANGE 150 TO 690 P.S.I.A., IN THE PRESENCE OF A CATALYST CONSISTING ESSENTIALLY OF A TICL3 COMPOSITION AND DIETHYL ALUMINUM CHLORIDE, SAID TICL3 COMPOSITION HAVING THE FORMULA 3TICL3.ALCL3, THE IMPROVEMENT IN WHICH THE SAID TICL3 COMPOSITION HAS A PARTICLE SIZE OF AT LEAST ABOUT 150 MICRONS WITH EXCLUSION OF PARTICLES OF A SIZE LESS THAN 150 MICRONS, WHEREBY LARGE DISCRETE PLATELETS OF POLYMER ARE PRODUCED AND FOULING IN SAID ZONE IS SUBSTANTIALLY ELIMINATED. 